Half of All Women Are Making a Mistake When Spacing Their Children

Summary: A new study found that one in two women aren't following doctors' recommendation to wait at least 18 months but less than 60 months after having their last baby before conceiving again, which is better for a healthy, full-term pregnancy.

You love being the mom of one, but you're longing to give your child a sibling — and the idea of having them close in age feels right. Before you try for baby number two (or three or four!), though, make sure you're timing it right: Doctors advise waiting at least 18 months after giving birth before getting pregnant again. That's because women who get pregnant within 18 months after their last child's arrival are at a higher risk of complications, including having a premature and/or a low birth weight baby. Waiting longer than 60 months between births is also associated with the same elevated risks, according to a new report by the Centers for Disease Control and Prevention (CDC), a study in the Journal of the American Medical Association (JAMA) and other research. Preterm birth, in turn, can sometimes lead to health problems for a newborn, including developmental and growth delays, a higher susceptibility to germs and learning difficulties, among other issues.

But a staggering one in two American women aren't following that recommendation, the CDC study showed. The agency found that 29.6 percent of women are conceiving their next child less than 18 months after their last one was born, and 20.7 percent wait 60 months (five years) or more. The final 49.7 percent get pregnant between the recommended 18 and 59 months after their last baby. Of course there are many important considerations that go into planning out your pregnancies, including financial and other logistical concerns — but from a purely medical standpoint, it's best to keep within the 18 to 59-month time frame.

The CDC relied on 2011 birth certificate data from 36 states and the District of Columbia, along with stats from its own National Survey of Family Growth, which looked at factors affecting birth and pregnancy rates between 2006 and 2010 from a sample of more than 22,000 American men and women.

The new findings show some interesting trends on how location, age and race can affect spacing between babies. South Dakota had the highest number of women who didn't wait 18 months to get pregnant (34 percent), while California had the lowest (26 percent). The under-20 set was more likely to ignore doctors' advice, only waiting between 11 and 14 months to get pregnant with their next baby. Women 40 and over had the longest intervals between their last child and next pregnancy, from 39 to 76 months. White women had the smallest gaps between babies (26 months on average), Hispanic women had the largest (34 months), and black women were in the middle (30 months).

Why shorter intervals between babies are linked to premature birth isn't completely clear — and there is debate about whether the actual interval itself is to blame or it's caused by other unrelated factors. Doctors theorize, however, that it could be because the body hasn't had enough time since the last pregnancy to replenish the vitamins and nutrients it needs for the next one. Inflammation in the uterus, which happens when a woman is expecting, might also linger when pregnancies are timed too closely.

What this means to you. How far apart to have your children is a personal decision, and many factors go into making the best choice for your family. Most doctors recommend waiting at least a year before you start trying for your next baby, and considering the preterm birth risks associated with getting pregnant faster than that, it's important to try to heed that advice. Do remember, though, that while preemies are generally two months behind full-term babies, the issues typically clear up by age 2. Beyond that, spacing your kids closer together has its benefits and downsides, as does having them farther apart. What's right for you depends on your specific situation. If you've already had a preemie or have a high preterm birth risk for other reasons, your doctor will likely recommend that you wait a bit longer to try again. When in doubt, talk to your OB-GYN with any questions or concerns you have about when to get pregnant again, so that you and your body are ready to go by the time it happens.

Catherine Donaldson-Evans is senior editor at What to Expect, specializing in pregnancy health, child development and parenting. She's the mom of a little girl and boy (good thing they're cute). In a past life, she was a news and entertainment reporter who traveled to faraway lands in her free time. Now she forgets what "free time" means.